Oslo police are hoping that the man, who is calling himself John Smith until his memory returns, will be identified by the public.

Mr Smith speaks fluent English but with an east European accent and understands Czech, Slovak, Polish and Russian. Despite suffering from apparent amnesia the man can also think clearly and reason.

He was discovered in an industrial area of Oslo, is believed to be aged in his twenties and may have been a victim of crime, police told the Norwegian VG newspaper.

Authorities have been trying to determine the man's identity for four months by sending photos and finger prints to East European police forces via Interpol and searching through missing people databases. They say the man has since has agreed with police to seek the public's help in trying to identify him.

In a statement, police said: "The man has no identity papers, and does not remember his name, where he came from, how he ended up in Norway or any other details of his life.

"[He] is of European origin, speaks very well English with a Eastern/Central-European accent, and understands Czech, Slovak, Polish and Russian languages. He is 187 cm [6.1 ft] tall, has blue eyes and dark blonde hair."

Amnesia involves either the partial or complete loss of memory and is commonly associated with brain damage, disease, or psychological trauma.

His case is being handled by the violence and sexual crimes branch of the Norwegian police, according to the BBC.

Last year Robin van Helsum, a Dutch citizen who is now 21, turned up at Berlin’s town hall in September 2011 saying he had lived five years in the woods.

But van Helsum’s real name was finally revealed when officials put his photograph online last year on what they assumed was his 18th birthday. A friend identified him almost instantly as a 20-year-old from the town of Hengelo in the Netherlands.

He was ordered to do 150 hours’ community service for carrying out his elaborate hoax, which cost the taxpayer £25,000.